The present invention relates to the treatment of vascular disease during either surgery or percutaneous angioplasty and stenting. More particularly, the invention relates to a system that reduces macro- and micro-embolization during the treatment of vascular stenosis.
A variety of surgical and non-surgical procedures have been developed for removing obstructions from blood vessels. Balloon angioplasty utilizes a balloon-tipped catheter which may be inserted within a stenosed region of the blood vessel. By inflation of the balloon, the stenosed region is dilated. Surgery involves either removing the plaque from the artery or attaching a graft to the artery so as to bypass the obstructing plaque. Other techniques, such as atherectomy, have also been proposed. In atherectomy, a rotating blade is used to shave plaque from an arterial wall.
One problem common with all of these techniques is the accidental release of portions of the plaque or thrombus, resulting in emboli which can lodge elsewhere in the vascular system. Such emboli are extremely dangerous to the patient, frequently causing severe impairment of the distal circulatory bed. Depending upon the vessel being treated, this may result in stroke, myocardial infarction or limb ischemia.
During a postoperative period vascular filters are used, when there is a perceived risk of the patient encountering a pulmonary embolus resulting from the lots generated at the surgical site. As a typical use of vascular filters, the filter is mounted in the vena cava to catch large emboli passing from the surgical site to the lungs.
Permanent implantation of a filter is often medically undesirable, yet it has been done because vascular filters are implanted in patients primarily in response to potentially life threatening situations. Accordingly, permanent implantation of a vascular filter is often accepted.
Nonetheless, avoid permanent implantation, it would be desirable to provide an apparatus and method for preventing embolization associated with conventional surgery and angioplasty procedures. In particular, it would be desirable to provide a device which could be located within the vascular system to collect and retrieve portions of plaque and thrombus which have dislodged during the surgery or angioplasty procedure.
This invention provides a vascular filter system for reducing macro- and micro-embolization.
It also provides a vascular filter system which is readily removable from the vascular system of a patient when the filter is no longer needed.
Further, it provides a vascular filter system having a configuration which does not require hooks to penetrate and grip the blood vessel walls, so that filter deployment results in less blood vessel injury.
Further the invention provides a vascular filter system of very low profile which is delivered along a guidewire and can be used in small vessels.
The invention will become more readily apparent from the description below.
The present invention generally relates to a vascular filter system useful in the treatment of vascular disease, in particular, a percutaneous angioplasty and stenting system useful, for example, in the treatment of carotid arterial stenoses. Macro- and micro-embolization occurs during such angioplasties, which increases the risk of stroke. The system of the present invention is useful in preventing such risk. This system is also useful in any procedure in which embolization is a risk.
The vascular filter system of the present invention decreases embolic events while allowing distal tissue perfusion. The filter is incorporated into a guidewire which is used during the entire procedure, from first crossing of a lesion through deploying a stent. In one embodiment, the filter consists of a thin membrane attached to the guidewire and supported by fine metal spines. Attachment of filter to guidewire allows membrane expansion, to provide a firm fit inside the artery. Also, the system allows collapse of the filter membrane at the end of the procedure, so that it fits tightly against the guidewire and is withdrawn through the guide catheter.
In another embodiment, the membrane rests upon or is attached to a basket-like structure, at least one end of which is attached to the guidewire. The membrane has a pore size such that blood flow is not impeded when the filter membrane is expanded, but through which micro- and macro-emboli are blocked. Expansion of the filter membrane is aided by the forward flow of blood against the filter. The filter design results in a very low profile so that the initial crossing of the lesion via the guidewire is minimally traumatic. Also, small diameter and narrow profile facilitate use of the device in smaller or larger arteries with minimal or no obstruction of blood flow.
Further embodiments of this filter membrane and its deployment system are provided without departing from the general nature of the guidewire based system. Among those are various modifications of the folding made to the filter membrane, and its configuration.